Adjustable rotary pump with pressure relief



Sept. 8, 1970 I H. LINCKS ET AL 3,527,552

ADJUSTABLE ROTARY PUMP WITH PRESSURE RELIEF Filed Oct. 22, 1968 6 Sheets-Sheet 1 Fig.1

Fig. 2

Sept. 8, 1970 H. LINCKS ET AL 3,527,552

ADJUSTABLE ROTARY PUMP WITH PRESSURE RELIEF Filed Oct. 22, 1968 6 Sheets-Sheet 2 207 209 243 FIG.3 242 241 240 Sept. 8, 1970 I c s ET AL 3,527,552

ADJUSTABLE ROTARY PUMP WITH PRESSURE RELIEF Filed 001;. 22, 1968 6 Sheets-Sheet 5 FIG. 5

Sept. 8, 1970 H. LINCKS ET AL 3,527,552

IEF

ADJUSTABLE ROTARY PUMP WITH PRESSURE REL Filed Oct. 22, 1968 e Sheets-Sheet FIG. 6

Sept. 8, 1970 H, c s ET AL 3,527,552

ADJUSTABLE ROTARY PUMP WITH PRESSURE RELIEF Filed 1968 6 Sheets-Sheet 6 FIG. 7

Sept. 8 1910 UNCKS ET AL 3,527,552

ADJUSTABLE ROTARY PUMP WITH PRESSURE RELIEF Filed Oct. 22, 1968 6 Sheets-Sheet United States Patent O US. Cl. 418-24 11 Claims ABSTRACT OF THE DISCLOSURE A rotary pump which includes means for varying the size of the intake and discharge zones so as to facilitate adjustment in the delivery flow of the pump. Surrounding the rotor are two concavely shaped adjustable jaws which are positionable relative to each other and to the axis of rotation of the rotor. Relative movement of each of these jaws produces a corresponding change in the volume of the intake and discharge zones. Means are provided for initiating such movement within relatively close tolerances. The pump additionally includes a pressure relief groove which extends along the inner surface of the jaws adjacent the intake zone of the pump. This relief groove serves to provide a means of equalizing the pressure distribution across the impeller blades. In this manner the hammering which such blades subject to the walls defining the pump zones during their transition from high to low pressure zones is minimized.

BACKGROUND OF THE INVENTION This invention generally relates to a rotary pump which includes improved adjustment features and a pressure relief means. The illustrated embodiment includes blades which are radially shifted with respect to the rotor body. The pump further includes adjustable jaws which are moveable along a defined path so as to permit ready adjustment of the size of the discharge zone.

Various types of pumps have been suggested which include elastic as well as radially adjustable bearing surfaces. Such devices usually include two dividers or abutments which separate the intake and discharge zones. One of these dividers is usually stationary while the other is radially adjustable. Alternately, prior pumps have included elastic parts which are unilaterally clamped and span the interstices. The blades move uniformly at any selected pump output. With respect to such an arrangement there are generally two abutments which are curved in shape and rest upon a stationary block. Due to the system elasticity there may occur a distortion of the discharge zone of the pump. If the pump is to be used in high pressure applications such elastic constructions are generally unsatisfactory as they do not permit accurate regulation of the delivery rate. Under such conditions the elastic elements of the pump often produce a continuous vibration, and therefore adversely effect the accuracy and regulation of the pump. Furthermore, with respect to such arrangements, the various mating surfaces must be machined and finished to very close tolerances. With respect to such arrangements the elastic ring may be caused to move from its null position between the stationary blocks and thus produce an annular slit. Such a condition greatly increases operating noise.

Conventional rotary pumps usually feature radially adjustable housing channels which are provided for conveying the pressurized oil; however, such arrangements reduce the space within the housing available for the ice remaining components. Under high pressure conditions the oil flows across the channels and thus creates a lubricated surface across which the upper edges of the pumping blades, which become deformed within the suction zone, pass. In this manner a pressure relief path is created. In an effort to prevent such blade deformations and the resulting pressure relief the individual components of the blade must be of relatively large construction. Under such situations the weight and space requirements of the structure often become extremely large.

Additionally prior rotary pumps which include a complete elastic ring for use as a boundary for the delivery space frequently lose adjustment in use. Such arrange ments are unsuitable for pumps delivering high pressure output and requiring close flow regulation. The illustrated embodiment overcomes such problems advantageously and includes means for assuring suificient lubrication even at zero delivery rates. Further the hammering action of the delivery blades, which occurs occasionally under high pressure conditions is drastically reduced.

In accordance with the illustrated embodiment, a semicircular recess is defined by the running jaws and continues beyond the region of the outlet slits in the form of an Archimedes spiral. The jaws may if desired be fabricated of cast plastic material. This spiral intersects with a straight edge to form a tangent thereto thereby forming a tapered end or tip. Additionally in the region adjacent each of such tips are pressure relief grooves which extend into the corresponding intake zone.

The illustrated embodiment of this invention includes straps which are arranged within recesses defined by the semicircular jaws. The straps are preferably fabricated of hardened spring steel or of a suitable resilient synthetic plastic, in a manner to facilitate replacement. The tips of the blades upon entering the pressure relief zones are forced outwardly against the internal surface of the surrounding walls. One end of the strap is attached to the gliding surface of the respective jaw, whereas the remaining end tapers forming a pointed tip. In this manner, noise is considerably reduced and transitional loads avoided.

The illustrated embodiment results in a substantial reduction in the cost of the adjustable jaws is incurred. The jaws need not be polished nor provided with any hardening treatment. Further, transitional radii at the recesses are not required as has been the case with respect to prior pumps. Further the features of the illustrated embodiment permit those parts which exhibit the greatest frictional wear to be easily replaced. The characteristics of the plastic material which is suggested for the construction is dictated by the quality of the pressurized fluid and its respective magnitude. The particular advantage of the illustrated embodiment is its light weight, and reduced frictional force.

An alternate embodiment of this invention includes a means for adjusting of the volume of the output zone in a manner which permits both jaws to be simultaneously and uniformly controlled by a single control piston and a single actuation member.

In accordance with the preferred embodiment, the piston rod acts upon a slidingly supported fork. The internal faces of the prongs of the fork are formed as inclined surfaces and function to radially position a pair of regulating pins. Thus the jaws may be adjusted by a simple mechanical means.

Other features and advantages of this invention will become apparent through reference in the following description and accompanying drawings.

FIG. 1 is a sectional view of a rotary pump illustrating certain features of this invention.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1.

FIG. 3 is a schematic of the jaws in the null or zero pump position.

FIG. 4 is an enlarged fragmentary view of FIG. 3 illustrating the tip construction of the jaws.

FIG. 5 is a plan view of the jaws of the pump of FIG. 1 illustrating the development of the delivery chamber.

FIG. 6 is an enlarged partial sectional view along the horizontal plan of the embodiment illustrated in FIG. 1.

FIG. 7 is a full sectional view of a rotary pump illustrating an alternate embodiment of this invention.

FIG. 8 is a full sectional view of a rotary pump i1- lustrating still another alternate embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With respect to the embodiment illustrated in FIG. 1, the rotary pump includes several sections which form an intake housing 1 at the intake side of the pump and form an exhaust housing 2 at the exhaust side thereof.

I Secured about the housings 1 and 2 is a delivery conveyer frame 3 secured by means of screws and alignment pins 5. Within the frame 3 are a pair of mating jaws 6 and 7 which are arranged so that they may be radially shifted. The semicircular running surfaces 9 and 10 of the jaws 6 and 7 form an output zone 8. The relative movement of the running jaws 6, 7 produces an adjustment in the volume of the output zone 8. Thus, it is appreciated that the zone 8 may be decreased or enlarged as the cross sectional area defined by the surfaces 9 and 10 varies between that of a circle and that of an oval as illustrated in FIG. 1. As the volume of the output zone 8 is varied, the pumping blades 13, which are spring biased outwardly will be urged toward the center of the rotor body 14. By this rather simple arrangement it is possible to selectively vary the volume of the output zone of the pump. The delivery rate can be easily adjusted by either varying the regulation of the pressure or by changing the driving power supplied to the pump. Serving this end, liquid pressure is applied to the control pistons and 16 and then flows through the fluid tubes 17 and 18. Radial movement of the pistons 15 and 16 produces a corresponding shift in the regulating pins 20 and 22 and in the jaws 6 and 7.

The jaws 6 and 7 are similarly shaped and are shifted with respect to the rotor. During movement the jaws 6 and 7 provide mutual support by means of their mating guide surfaces 11 and 31, and 12 and 32 respectively. The guide surfaces 31 and 32 are constructed as the tangential elongations of the one end of the semicircular surfaces 9 and 10. The surfaces 11 and 12 extend tangentially from the outer surfaces of the opposite end of the jaws 6 and 7 respectively.

In order to reduce the weight of the pump, and also in order to increase the manufacturing feasibility, the running jaxws are preferably fabricated of cast plastic. Such a material resists wear and tear, and exhibits a much lower specific gravity than suitable metallic materials. Further, such plastic materials can usually be cast within narrow dimensional tolerances, thus eliminating any refinishing operations. Serving to regulate output fiow are spring groups 21 and 22. The delivery rate is manually adjusted by means of a regulation means 23. Rotary actuation of a handwheel 24 increases the pressure within a cylinder 25. This pressure variation is transferred through conduits 26 to the pistons 15 and 16 and upon the regulation pins 19 and 20. In this manner, the jaws 6 and 7 are caused to shift, thus razing the volume of the delivery zone and produce a regulating effect upon the output of the pump as previously mentioned. As illustrated in FIG. 2, adjustment of fluid flow through the channels 17 and 18 is accomplished by means of adjusting screws 27.

With respect to FIGS. 3 and 4, the inwardly disposed semicircular recesses 209, 210 of the jaws 206, 207 are illustrated. The recesses extend along a major section of a curved face and thus extend fully across the intake and delivery zones. Proximate the discharge slit 230 of the delivery zone the path of the recesses 209, 210 are formed into the arc of an Archimedes spiral and extend to a point 241 at which a straight line 242, extending from the run-out tip 243, forms a tangent therewith. As a result of this particular development, the blades 213 are urged in a predetermined manner towards the center of the pump and in this way force the oil located in the chambers 250 (FIG. 5) of the rotor body 214 under pressure into the bushings. In this manner sufficient lubrication of the bushings is assured even though the jaws 206 and 207 are in their null position.

Under certain conditions a hammering condition may arise due to the development of a pressure differential across the impeller blades 213. This condition arises when high outlet pressure which exists in the delivery chamber 250 is decreased before the impeller blade 213 has passed the transition point. In an effort to reduce such hammering, the transition point of the jaws 206 and 207 is located at the tips 243 wherein run out relief grooves 251 are provided for communication with the output spaces. The grooves 251 extend to the intake zone of the pump and sample up small amounts of oil which thus produces an immediate drop in pressure, the pressure differential.

Serving to reduce noise and to avoid the creation of transitional loads, a pair of running jaws 6 and 7 are provided as illustrated in FIG. 7. The jaws are provided with semi-circular recesses 9 and 10. Each of the cutouts extends to force a tip with its respective surface 11 or 12. Within the recesses 9 and 10 are located guide straps 33 and 34. More particularly, the strap 34, which is located within the cutout 10 of the running jaw 7, is secured at one end 35, by securing means 30 in the form of a bolt or alternatively adhesive to the sliding surface 12 of the running jaw 6. The remaining end 36, tapers to form a tip, and lies, due to its natural resiliency, against the strap 33. Strap 33 includes an end 37 which is secured by securing means 38 to the sliding surface 11 of the running jaw 7. The end 39 which is similarly formed with a taper lies against the strap 34. It 'will be appreciated that the ends 36 and 39 of the straps extend so that their tapered ends follow in the direction of rotation of the impeller 14 thereby providing a stepless transition for the delivery blades 13.

As the jaws 6, 7 are shifted, the tapered ends 36, 39 of the straps will slide along the internal surface of the opposite straps 33 and 34 respectively and thus facilitate adjustment of the delivery rate. In addition to those advantages previously listed, it should be noted that construction of the pump is greatly facilitated when compared to prior pumps since greater tolerances are acceptable and since a slight inaccuracy in the machinery of the sliding surfaces will not greatly reduce influence of the performance of the pump.

With respect to the embodiment of FIG. 7, the straps may be constructed of spring steel or of plastic. They are urged by the centrifugal force of the impeller blades against the jaws. The length of the straps 127 and 131 are selected on the following basis. The run-out tips 131 and 132 preferably extends into the pressure relief zones 200 and 201, and then extend into the internal face 202 of the housing. In this rather simple manner a majority of the transitional stresses and strains upon the pump are avoided.

With respect to FIG. 8 the interior of a pump housing 303 is illustrated containing two jaws 306 and 307, which are adjustable to facilitate variation in the volume of the output zone as determined by the position of the regulation pins 319 and 320. The pins 319 and 320 are positioned with the aid of a sliding supported fork 341 including prongs 343 and 344. The surfaces of the prongs 343 and 344 adjacent to the regulating pins 319 and 320 display inclined faces 342.

For illustrative purposes it is assumed that the cylinder 318 and the piston 316 are actuated by hydraulic, pneumatic or mechanical means. As the piston rod 330 is moved in the direction of the delivery frame 303, the movement is transferred across the fork 341 to the regulation pins 319, and 320. The pins then produce a readjustment in the position of the jaws 306 and 307. This particular construction prevents the jaws from sliding disproportionately when the various adjustment steps are actuated. Both halves of the jaws, during such adjustments, are caused to change their positions simultaneously and in an identical manner. Although two embodiments of this invention have herein been shown and described, it will be uderstood that certain details of the construction shown may be altered without departing from the spirit and scope of this invention as defined by the following claims.

We claim:

1. An adjustable rotary pump having pressure and output zones and including rotor blades which are radially shiftable and further wherein the volume of the output zone may be selectably adjustable with the aid of slidable jaws, the improvement comprising symmetric semi-circular recesses upon the inwardly disposed surfaces of said jaws, means for shifting said recesses concentrically with respect to the rotor, a portion of the surfaces of said jaws being in sliding contact with each other and maintained within the housing of the pump wherein each of the jaws are developed in the region adjacent the delivery zone of the pump in the shape of an Archimedes spiral so as to provide a tip at the point of intersection with the outwardly disposed edge of the jaw.

2. A rotary pump in accordance with claim 1 which further includes relief grooves within the inwardly disposed surfaces of said jaws adjacent said tips and which extend into the intake zone of the pump.

3. A rotary pump in accordance with claim 2 wherein the jaws are cast of a plastic synthetic material.

4. A rotary pump in accordance with claim 2 wherein the inwardly disposed surfaces of said jaws define longitudinal recesses and elongated resilient straps positioned within said recesses.

5. A rotary pump in accordance with claim 4 wherein the ends of said straps extend beyond the discharge zone and include a sharp edge which is in contact with the internal surface of the housing.

6. A rotary pump in accordance with claim 5 wherein one end of each of the straps is secured to the outwardly disposed surface of the jaws at a point adjacent the point of sliding contact of the jaws and the remaining end of each strap tapers to form a tip.

7. A rotary pump in accordance with claim 1 which further includes a common steering piston for controlling the size of the delivery zone defined by said jaws in a simultaneous and uniform manner.

8. A rotary pump in accordance with claim 7 wherein said piston acts upon a fork, said fork being supported for movement with respect to said pump, said fork defining facing, inclined surfaces in sliding contact with respect to positioning means associated with said jaws so that relative movement between said fork and said pump will produce a corresponding relative movement of said aws.

9. A rotary pump as set forth in claim 8 wherein the steering piston is driven by mechanical means.

10. A rotary pump as set forth in claim 1 which further includes a pair of jaws defining inwardly disposed semicircular guide paths and each jaw defining a first and second mating surface. said first mating surface of each of said jaws being in the form of a tangential extension of one end of the semicircular guide path and whereas said second mating surface of each jaw being an extension of the outside surface of the opposite end of the semicircular guide path.

11. A rotary pump as set forth in claim 1 which further includes a pair of adjusting pistons each of which is positioned for cooperative movement against one of said jaws, and a hydraulic means for actuating each of said pistons in a simultaneous uniform manner to permit uniform adjustment of said jaws, said hydraulic means including a fluid pressure source and fluid conducting conduits between said source and said piston.

References Cited UNITED STATES PATENTS 2,170,786 8/1939 McElroy et a1.

2,238,786 4/1941 Warman.

2,313,075 3/ 1943 Kendrick et al.

2,631,544 3/1953 Wilcox.

2,646,003 7/1953 Ferris.

3,266,429 8/ 1966 Stockett.

3,407,742 10/ 1968 Mitchell et a1.

DONLEY J. STOCKING, Primary Examiner W. I. GOODLIN, Assistant Examiner US. Cl. X.R. 418179 

